Had a question at an old post about the Remington 512,

Specifically asking about mounting a scope, and if you'd need a gunsmith.

WARNING: I am not a gen-u-wine, officially certified gunsmith: this is what I've picked up over time. This is one of those "Do it right the first time, or not at all" things, so if you're going to try it, make sure you've studied it, that you understand exactly what you're doing, that you get/get access to the proper tools, and that you take the time to do it right.

First off, the gentleman is asking for a relative in India. I have no idea what, if any, regulations there are on parts like this(scope bases, drill bits, taps, rings, scopes) being shipped to India; if he buys them locally, no problem(tap and bits shouldn't be any problem, so many of them COME from India nowadays). If he needs to order them, the company should be able to help him figure it out. India being a friendly country, I doubt any problem, but check to be sure if you’re sending them to him. (Gun Parts has a one-piece base for this rifle, the same one I used on mine)

As to whether needs a gunsmith, depends on what tools he has access to and if they feel up to trying this. At the base level, it’s pretty simple:
Remove the barrel/receiver from the stock.
Clamp it in a suitably padded vise and make sure it’s absolutely square and level in both axes, preferably on a drill press table, or milling machine table.
Set the base/s in place and lock them somehow so they’re square and level.
Use a punch to mark where the holes need to be drilled.
Remove base/s and drill the holes.
Thread the holes.
Clean out thoroughly, all cutting oil and chips.
Install bases.

Like a lot of things, basically straightforward. The trouble comes in keeping everything right at each step. Here it's critical to
Keep the receiver level
Make sure the base/s are level/square and do not move while marking the drilling spots
Make sure the drill does not wander while drilling
Do NOT drill too deep
Run the tap straight while cutting the threads.

You really need a drill press and vise; they make both squaring & leveling and drilling a LOT easier and more precise. For a centerpunch to mark the spots for the drill to bite, there are punches made just for the purpose: different diameter shafts with the punch point in the center. You find the one that will just fit inside the holes in the base, set it in the hole and tap to mark the spot. You can take a pin punch, carefully grind a centered point on the end at a very shallow angle, then carefully grind the diameter(belt sander or grinder) so it’ll barely fit the hole and use it. Or,

You can use the scope base for a drilling guide: level the receiver, set the base in place and clamp it so it cannot shift out of place and use the bases as a guide for the drill. If you do that, be careful; many of the bases are aluminum and relatively soft, and you can damage the side of the hole if the bit is just a touch off center. I have heard of gunsmiths using superglue for this instead of a clamp; clean the top and the bottom of the bases absolutely clean and then glue on square and level; after the glue sets drill the holes.

He’ll have to set the press so the hole depth is just deep enough; one thing that cannot be fixed(short of a new barrel, really) is drilling through into the chamber.

Generally, screws for mounts are threaded 6x48, a small, fine thread and not to be found at most tool places(they can be found at Brownell’s or Midway). They’re easy to break, so use lots of cutting oil and go slowly, in a ¼ to 1/3 turn and then back up. Make one turn at most, then all the way out and clean chips from the hole, relube and go back in. You can chuck the tap into the drill press and use that as a guide to help make sure the tap goes in exactly vertical.

If he has some shop skills and can take it slow and careful, he can probably do it himself. If he has any doubts at all, find a gunsmith. With the right tools and experience, a simple job for the smith.

Please note, this is a very short & dirty ‘how it works’, not an in-depth how. If he’s interested in more details, I’d recommend the Gunsmith Kinks books from Brownells. Lots and lots of tips from gunsmiths on just about everything from mounting sights to bluing to trigger and stock work. And I make this sound possibly worse than it is, but understand that with a scope base you really have no wiggle-room: if you have it a little to one side or the other, the scope will be off-center and that's bad. If you're using two-piece bases and they're not aligned exactly, the rings won't be in line and that's bad. If you get one hole in the right place and your mark for the second turns out to be a little off, that's bad. I've done this job a couple of times and practically sweated blood at some points, checking and rechecking to make sure it was right.

His other question was any scope I'd recommend. You want to start a LONG argument(assuming the moderators don't kill it), go to any gun board and ask that question. My opinion:
For general use on a .22, get either a 4x or, if you want a variable, a 3-9x; for anything but a match rifle that's plenty of magnification. Go with a known brand(Weaver, Bushnell, Tasco and such), and you shouldn't have any problems with it. Most scopes will have either a 1" tube or a 30mm; make sure you get the rings to match.